Abstract:

Based on daily and monthly sea ice concentration data, obtained from the National Snow and Ice Data
Center, the 15% sea ice concentration limit in the Beaufort Sea was used as a threshold to determine the location
of the sea ice edge. After extracting the sea ice edge, we calculated the sea ice concentration, sea ice
extent, and sea ice area. We then analyzed the spatiotemporal variabilities and trends of the retreat of the ice
edge in the Beaufort Sea through interannual and seasonal changes. The results showed that sea ice concentration,
sea ice extent, and sea ice area in the Beaufort Sea during 1978–2015 all had significant trends of
reduction. During the study period, sea ice concentration decreased by an average of about 0.3%·a–1, sea ice
extent decreased by an average of 3 235 km2·a–1, and sea ice area decreased by an average of 5 084 km2·a–1.
Sea ice concentration during 1979–1996 showed no significant trend of decrease, although a trend of reduction
was evident during 1996–2015. The sea ice extent in the Beaufort Sea is at its maximum between November
and May (full ice coverage) and at its minimum in September. The sea ice area reaches its minimum
in September and its maximum in December or January. The time of minimum sea ice extent appears to have
become delayed. The state of total ice cover has tended to begin later, end earlier, and its duration (average:
212 d) has become shorter.

Key words: Beaufort Sea, passive microwave remote sensing, sea ice extent, sea ice concentration, spatiotemporal variability